One question that comes to mind with all this talk about character is: Are the standards for mc likability different in children's fiction or when the mc is a child?
Even with a child we probably won't tolerate whininess or undue stupidity. But as far as character arc goes, aren't most stories about children coming of age stories in some sense or another? The character growth often seems pretty clear, or clearer than with adult characters. Children can't help growing from new experiences. It's what they're built to do.
Adults seem to have to be dragged into it kicking and screaming. And that's the set-up for the reluctant hero. (I'm a sucker for a good reluctant hero.)
Really, my question is: Do we want anything different from our child mc's than our adult mc's?
In some ways I feel our child mc's have a harder time than adult ones. They have to act like children in order to be believable, but they also have to delve into adult problems, concepts and philosophies in order to be interesting to an adult audience (which we also want from our children's literature).
And one more question: Who are your favorite child characters?
I'll start. I love Scout. And as a kid, I especially loved Kate from the Good Master.